Asthma is a disease which involves T cell recruitment and activation of specific T cell subtypes. Cytokines released by inflammatory and epithelial cells in the airway mediate this response. These cells synthesize and secrete proinflammatory and immunomodulatory cytokines such as interleukins and granulocyte-macrophage colony stimulating factor(GM-CSF). Elevated levels of GM-CSF have been demonstrated in the bronchoalveolar lavage fluid and epithelial cells of atopic patients after an allergen challenge. GM-CSF regulates the recruitment, phenotypic differentiation and activation of dendritic cells. In the lung, elevated levels of GM-CSF have been shown to be associated with dendritic cell accumulation. This study will examine the hypothesis that subjects with mild atopic asthma have increased intraepithelial cells compared to normals. It will also examine whether the intraepithelial dendritic cells of atopic asthmatics display activation markers that differ from normal controls. The Core Laboratory was utilized for laminar flow hoods, BAL, Northern analysis, oligonucleotide synthesis, PCR, ELISA, Recombinant DNA techniques, RNA isolation, Western analysis, and ultracentrifugation.